Calling a function that does not exist via reflection/javassist

Question

i need to call a function - (getters and setters of a property), but my problem is, the name of the property is generated at runtime (name of some variable + number).

Is it possible to manipulate the bytecode via javassist or gclib so that the function calls are directed to some proxy object/function, and there the real method name and the number extracted from the called function name, so that i can call the function afterwards (with the number as parameter)?

I tried the following, but it didnt work:

MethodHandler handler = new MethodHandler() {
        @Override
        public Object invoke(Object self, Method thisMethod, Method proceed, Object[] args) {
             String realMethodName=thisMethod.substring(0,5);
             Integer param=Integer.parseInt(thisMethod.substring(5));
            Method m = self.getClass().getMethod(realMethodName);
            m.invoke(self,param);
            return null;
        }
    };

Answer 1

I think this might be one of the few scenarios where using Java reflection Proxy objects might come in handy.

You could define some interface, but delegate the method to the (dynamic) invocation handler which would then call those "getter/setter" methods.

Side note: when implementing such an invocation handler you have to understand that ANY method call on the corresponding object will trigger its "invoke" method; event when you call toString or equals or whatever else is inherited from Object.

EDIT: and one more (different) thought: are you sure you need to create dynamic method names at all? If you have some numeric (or string based) key - what not using a Map for example?

Like

    Map<WhateverKeyType,YourPropertyClass> 

that would be much more "normal java" way of handling your problem (instead of thinking about reflection or byte code manipulation).